Dear authors,
thank you for the revision of your manuscript, and for carefully addressing the reviewer’s comments. I was hoping that the reviewers would have commented on a few more, critical points which I myself identified with my own review. But as this is not the case, I would like to ask you to consider and discuss the following points before I recommend the manuscript for final publication. Thank you!
Christian

- It is good that you discuss the differences between results from single-beam and scanning laser altimetry (p. 8 ff). I agree that your method will detect more ridge peaks along the same track length as a single beam laser. However, in general the statistical results should be very similar if sufficient flight track length is covered over ice with stationary statistical properties? In fact the original definition of the ice thickness pdf by Thorndike et al. considers area, not track length covered by a certain ice thickness class. Yet, the ice thickness pdf is mostly determined from one-dimensional measurements. You may also consider results from a study by Beckers et al. (2015) who compared single beam and scanning laser measurements over sea ice. They found that results (in that case rms rougness) were quite similar when sufficient track length was included.
- On page 22, line 12 ff you discuss results over landfast ice. However, I find the results and the underlying hypothesis unclear. Do you think landfast ice is mostly level? That’s clearly not the case in particular near the ice edge where a lot of deformation takes place as the fast ice edge growths seawards by addition of more and more pack ice. Therefore I would not necessarily expect that fast ice stands out in your observations (except in extreme cases, e.g. over lagoons or deltas or very near the shore). Please elaborate.
- Section 4.3: Relationship between sea ice thickness and surface feature variability
This is an interesting analysis, however, I wonder if your specific approach is valid. I am concerned that your ridge and thickness data are not independent, because both have been derived from the same freeboard measurement. However, comparing mean feature height with mean thickness (including level and ridged ice as you appropriately point out) separates different properties somehow. However, looking at Figure 12, one may expect that linear relationships between mean feature height and mean thickness may result in as good regression coefficients? That would not be surprising, because eventually variations in mean freeboard(thickness) are dominated by differences in the amount and height of ridges.
I am not sure that your analysis is suitable to demonstrate the square root relationship between ridge height and block thickness/level mother ice thickness. My understanding is that that relationship describes the conditions when ridges have just formed. Hence block size is representative of the level ice thickness at the time of ridge formation. However, in your case you don’t know how old the observed ridges are, and the surrounding level ice can have significantly grown since formation of the ridges, making the approach invalid? See also Amundrud et al. (2004) for more discussion.
Could you carry out linear regressions of the data in Figure 12 as well and compare with your results using the root-mean square relation? And can you please discuss possible uncertainties of your approach in a little more detail along the lines outlined above?
- P24, l13: should be feature height, not ice thickness? Please check all text for similar oversights.
- Figure 8 and elsewhere, x-axis label: Please write Vf (per unit area; m) in the axis label, not in the caption. That makes the figure more immediately readable.
- Figure 12 caption and corresponding text: Please be more specific: you compare MEAN feature height with MEAN ice thickness, correct? Also, maybe it’s better to write in the caption: Correlation between the IceBridge mean ice thickness than to refer to product.

Amundrud, T. L., H. Melling, and R. G. Ingram (2004), Geometrical constraints on the evolution of ridged sea ice, J. Geophys. Res., 109, C06005, doi:10.1029/2003JC002251.
Beckers, J.F., A.H.H. Renner, G. Spreen, S. Gerland, C. Haas (2015), Sea ice surface roughness estimates from airborne laser scanner and laser altimeter observations in Fram Strait and north of Svalbard. Annals of Glaciology, 56(69), doi: 10.3189/2015AoG69A717; http://www.igsoc.org/annals/56/69/t69a717.html